Basic Principle

Pumping operation of BTR series Roots effected through two ‘8’ shaped rotors in pumping chamber rotating opposite directions. With drive ratio of 1:1, two rotors constantly seal against themselves without touting each other and the chamber. The gaps between the movable parts are narrow enough to seal against the exhaust side and intake side in visous flow and molecular flow, so that to achieve the purpose of pumping the gas in the chamber.

When the rotors locate at 1 and 2 in the chamber, the volume of air inlet will increase. When the rotors locate at 3 in the chamber, part of air volume will be blocked out from the air inlet. When the rotors locate at 4, this volume will open to vent. When the rotors further, air will discharge through the air outlet. Rotors will rotors more than two course once every rotates.

The pressure difference between the inlet side and outlet side of roots pump are limited. BTR series roots pump adopts a bypass valve. When the value of pressure difference reaches to a certain figure, the bypass valve opens automatically. Some air volume from the outlet side flows to the reverse direction of inlet side through the bypass valve and reverse passage, which reduce the operational load of roots pump and front-stage pump greatly in the condition of high pressure difference. Meanwhile, due to the function of unloading when bypass valve opens, it makes sure BTR series vacuum pump and front-stage pump start at same time to avoid the overload for both of them.

The roots pump has to be worked as pump unit together with front-stage pump (such as rotating vane pump, slide valve pump and liquid ring pump). If it is required to reach to higher vacuum degree, two sets of roots pumps can be connected to work as a three stage roots pump unit.

Characteristics

1. There is zero friction between rotors, also between rotor and pump chamber, so there is no need of lubricating oil. Consequently, our pump can avoid the oil pollution on vacuum system.

2. Compact structure, and easy to install horizontally or vertically.

3. Good dynamic balance, stable running, small vibration and low noise.

4. Can pump off the non-condensable gas.

5. Quick started and can achieve the utmost pressure in a short time.

6. Small power and low operation maintenance costs.

7. The bypass value on roots pump can enjoy the automatic overload protection effect, so that the operation will be safe and reliable.

Application Ranges

1. vacuum drying and impregnation

2. vacuum degassing

3. vacuum pre-discharging

4. gas exhausting

5. for the processes in vacuum distillation, vacuum concentration and vacuum drying in chemical industry, medicine, food and beverage, light industry and textile industry

Why is the rotary lobe blower called a “Roots Blower”?

The positive rotary lobe blower was designed in the 1850s by the Francis and Philander Roots brothers. It was later patented in 1860 by the brothers and the Roots name became the name of the design.

What is the basic principle of a “Roots Blower”?

The roots blower’s principle consists of the following: the process starts with air flowing from the inlet port into the element chamber. The timed rotation of the rotors against the wall of the chamber creates a so-called “air flow direction”. At this point, there is still atmospheric pressure in these chambers.

As soon as the first lobe passes the opening to the pressure side, the system pressure is adjusted. This is called isochoric compression. The rotors seal each other off to the inside, which prevents a change of pressure.

How does a “Roots Blower” operate?

A Roots blower operates using the isochoric compression principle, also known as external compression. The pressure increase is achieved by intermittently transporting a gaseous medium (e.g. atmospheric air) into a system.

By forcing the medium from atmospheric conditions into a system with a given resistance (e.g. a water column, distribution network), the relevant pressure increase is achieved. The roots blower will operate at a controlled output level to overcome this resistance.